The present invention relates generally to refrigerators. More particularly, the present invention relates to a method of controlling the temperature in an ice compartment of a refrigerator.
It is now common practice in the art of refrigerators to provide an automatic icemaker. In a “side-by-side” type refrigerator where the freezer compartment is arranged to the side of the fresh food compartment, the icemaker is usually disposed in the freezer compartment and ice is usually dispensed through an opening in the access door of the freezer compartment. In this arrangement, ice is formed by freezing water with cold air in the freezer compartment, the air being made cold by the primary temperature control circuit or system of the refrigerator which includes an evaporator.
In a “bottom freezer” type refrigerator where the freezer compartment is arranged below a fresh food compartment, convenience necessitates that the icemaker be disposed in an ice compartment on the access door of the top mounted fresh food compartment and ice be delivered through an opening in the access door of the fresh food compartment, rather than through the access door of the freezer compartment. However, the air in the fresh food compartment is generally not cold enough to freeze water to form ice. Therefore, a working medium, such as air or a mixture of propylene glycol and water, is usually used to cool the icemaker. The working medium is delivered to the ice compartment through a secondary temperature control circuit to maintain the icemaker at a temperature below the freezing point of water.
More particularly, when the working medium is air, the primary temperature control circuit cools the air in the freezer compartment to a predetermined temperature. The cooled air is then supplied to the ice compartment from the freezer compartment through a secondary temperature control circuit which is operated in accordance with a selected thermodynamic cycle. In this case, the secondary temperature control circuit includes an air supply path extending from the freezer compartment to the ice compartment, an air return path extending from the ice compartment to the freezer compartment, and a fan or blower for moving the air in the supply path and the return path.
When the working medium is a food safe liquid in the nature of a mixture of propylene glycol and water, a different kind of secondary temperature control circuit is used. This kind of secondary temperature control circuit will be discussed in detail below when the exemplary embodiments of the present invention are described.
Putting the icemaker in the ice compartment on the access door for the fresh food compartment presents many new challenges not previously encountered because of the temperature difference between the ice compartment and the fresh food compartment. For example, if there is no ice in the ice compartment, then keeping the secondary temperature control circuit operating would certainly waste energy. On the other hand, if there is ice left in the ice compartment, the ice would melt if the secondary temperature control circuit is turned off (in some of the known “bottom freezer” refrigerators, turning off the icemaker will automatically terminate the operation of the secondary temperature control circuit). Upon melting, the water would leak within and/or out of the ice compartment. Of course, a user can find out whether the ice compartment has ice before deciding whether to terminate the operation of the secondary temperature control circuit, but such approach is inconvenient to the user because the user needs to open both the access door of the fresh food compartment and the access door of the ice compartment.